two new species of damselfishes (pomacentridae) - Western ...

Rec. West. Aust. Mus., 1976,4 (2)
TWO NEW SPECIES OF DAMSELFISHES (POMACENTRIDAE)
FROM WESTERN AUSTRALIA
GERALD R. ALLEN*
[Received 22 September 1975. Accepted 1 October 1975. Published 30 September 1976.]
ABSTRACT.
Two new species of damselfishes belonging to the genus Chromis are described
from Western Australia. C. megalopsis is described from two specimens
taken by bottom trawl in 70-85 metres near Bernier Island and off Cape
Cuvier. The salient features of this species include a large eye (2.3 to 2.4 in
head length) and exposed suborbital margin. C. westaustralis n.sp. is closely
related to C. fumea Tanaka from Taiwan, the Ryukyu Islands and Western
Australia. The two species are separable, however, on the basis of coloration,
maximum size, anal ray count, and the condition of the preopercle margin.
In addition to the description of new taxa, the species of Pomacentridae of
Western Australia, including 26 previously unrecorded forms, are briefly
reviewed.
INTRODUCTION
Pomacentridae is one of the largest families of reef fishes, containing
approximately 250 species. They occur primarily in the tropics, but several
are found at temperate latitudes. The distribution includes Atlantic,
Mediterranean, and Indo-Pacific reefs, but the majority of species are
confined to the latter region.
Whitley (1948) listed the following representatives from Western Australia
(if no longer valid present allocation indicated in parentheses): Actinochromis
victoriae Gunther (Parma victoriae); Amphiprion melanostolus
Richardson (A. clarkii Bennett); A. milii Bory de St. Vincent (A. clarkii);
A. rubrocinctus· Richardson; Chromis klunzingeri Whitley; C. scotochil-
*Curator of Fishes, Western Australian Museum, Perth.
133

A summary of counts for the dorsal, anal, and pectoral fin rays, gill rakers
on the first arch, and tubed lateral-line scales is presented in Table 2.
Type material has been deposited at the following institutions: Australian
Museum, Sydney (AM); Bernice P. Bishop Museum, Honolulu (BPBM);
British Museum (Natural History), London (BMNH); United States National
Museum of Natural History, Washington, D.C. (USNM); Western Australian
Museum, Perth (WAM) ..
Chromis megalopsis n.sp.
(Fig. 1; Tables 2 and 3)
Holotype. - WAM P25207-001, 84.1 mm SL, collected with bottom
trawl approximately 40 nautical miles west of Bernier Island, Western
Australia (24 0
59'S, 112°27'E) in 71 fathoms by R. George and crew of
"Dimantina" on 8 October 1963. .
Paratype
WAM P2234, 102.0 mm SL, collected with bottom trawl about 37
nautical miles northwest of Cape Cuvier, Western Australia (approximately
24 0
59'S, 113 0
OO'E) in 70-85 fathoms by J. Penn on 29 July 1972.
Diagnosis
A species of Chromis with the following combination of characters:
dorsal rays XIlI,15 or XIV,14; anal rays Il,12 to. 13; eye relatively large,
2.3 to 2.4 in ·head length. suborbital margin exposed. body depth 2.1 in SL;
colour generally pale, silvery or whitish on ventral half of body; small
diffuse dark spot on uppermost part of pectoral base and dark spot covering
most of outer face of pectoral axil.
Description
Dorsal rays XIIl,15 (XIV,14); anal rays Il,13 (Il,12); pectoral rays 19;
pelvic rays 1,5; gill rakers on first arch 8 + 20 = 28 (10 + 20 = 30); tubed
lateral-line scales 17; horizontal scale rows from terminal lateral-line scale to
base of dorsal fin 1-2; from lateral-line to origin of anal fin 9; procurrent
spines on upper and lower edge of caudal fin 2.
Body ovate, laterally compressed, the greatest depth 2.1 in the standard
length. Head profile conical, the head length contained 2.9 (3.0) in the
standard length. The following proportions are expressed into the head
136

Figure 1: Chromis megalopis holotype, 84.1 mm SL, west of Bernier Island,
Western Australia.
Figure 2: Chromis westaustralis, holotype, 84.0 mm SL, Abrolhos Islands,
Western Australia.
137

length: snout 4.0 (4.3), eye diameter 2.4 (2.3), interorbital width 3.5 (3.2),
least depth of caudal Peduncle 3.5 (2.3), length of caudal Peduncle 4.5
(3.7), of pectoral fin 1.0, of pelvic fin 1.1 (1.0), of caudal fin 1.0 (1.2).
Single nasal opening on each side of snout; mouth oblique, terminally
located; lateral-line gently arched beneath dorsal fin, terminating 1-2 scale
rows below base of last dorsal spine; lips, chin, isthmus, posterior and
inferior limb of preopercle, and area around nostrils naked; remainder of
head and body scaled; scales finely ctenoid; preopercle with two large scale
rows and additional row of small scales on inferior limb; small sheath scales
covering basal 1/2-2/3 of dorsal, anal, and caudal fins; edge of suborbital,
preopercle, and opercle entire except flattened spine at angle of opercle;
suborbital narrow, about 1/3 pupil diameter.
Teeth of jaws conical, multiserial, an outer row in each jaw consisting of
36 to 37 enlarged teeth and inner series of irregularly arranged smaller teeth;
height of largest teeth of upper jaw about twice nostril diameter.
Origin of dorsal fin at level of fourth tubed scale of lateral-line; spines of
dorsal fin gradually increasing in length to fourth, fifth, or sixth spine,
remaining spines gradually decreasing in length. The following proportions
are expressed into the head length: length of first dorsal spine 3.2, of fifth
dorsal spine 1.9, of last dorsal spine 2.8 (2.7); of longest soft dorsal ray 1.8;
of first anal spine 5.1 (3.7), of second anal spine 1.7 (1.5), of longest soft
anal ray 1.6.
The following proportions are expressed into the standard length: snout
to origin of dorsal fin 2.6 (2.4); snout to origin of anal fin 1.3 (1.5);
snout to origin of pelvic fin 2.3 (2.5); length of dorsal fin base 1.6, length of
anal fin base 4.3 (4.0).
Colour of holotype in alcohol: head and body mostly pale; upper part. of
head and back light brown; lower half of sides whitish or silvery with faint
dusky patches; fins yellowish-tan except slightly dusky on basal portions;
pectoral with diffuse dark spot on uppermost portion of fin base; pectoral
axil with dark spot covering most of outer face.
Remarks
This species is known only from the types. It is distinguished from
other species of Chromis on the basis of the combination of characters given
in the diagnosis. It is named megalopsis with reference to the unusually .
large eye.
138

Table 2: Selected counts for specimens of new Chromis from Western Australia
Pectoral Lateral-Line
Soft dorsal rays Soft anal rays rays Scales Gill Rakers
Species 1112131415 10111213 1920 17 1819 20 28 29 30 31 32 33
C. megalopsis 1 1 1 1 2 2 1 1
C. westaustralis 214 115 9 7 1 7 7 1 3 7 4 1 1
Table 3: Morphometric proportions (in thousandths of the
standard length of type specimens of Chromis megalopsis.
Characters
Standard length (mm)
Greatest body depth
Head length
Snout length
Eye diameter
Interorbital width
Least depth of caudal peduncle
Length of caudal peduncle
Snout to origin of dorsal fin
Snout to origin of anal fin
Snout to origin of pelvic fin
Length of dorsal fin base
Length of anal fin base
Length of pectoral fin
Length of pelvic fin
Length of 1st dorsal spine
Length of 7th dorsal spine
Length of last dorsal spine
Longest soft dorsal ray
Length of 1st anal spine
Length of 2nd anal spine
Longest soft anal ray
Length of caudal fin
140
Holotype
WAM
P25207-001
84.1
482
344
87
145
98
98
76
382
741
436
628
232
351
319
108
184
125
187
67
206
209
341
WAM
P2234
102.0
466
333
78
142
104
143
89
412
686
398
642
221
337
328
105
176
125
182
91
221
204
280

depth 2.3 to 2.5 in SL; preopercle margin smooth or crenulate without
distinctive serrae; colour generally light brown, darker dorsally with prominent
dark streak on each lobe of caudal fin; pectoral axil with black spot
extending on to upper half of external part of pectoral base; white spot
present at base of posterior soft dorsal rays in live individuals.
Description
Dorsal rays XIII,12 (X1II,1l to 12); anal rays n,ll (n,10 to 11); pectoral
rays 19 (19 to 20); pelvic rays 1,5; gill rakers on first·arch 9 + 22 = 31
(29 to 33); tubed lateral-line scales 19 (17 to 20); horizontal scale rows from
terminal lateral-line scale to base of dorsal fin llh; from lateral-line to origin
of anal fin 9; procurrent spines on upper and lower edge of caudal fin 2.
Body relatively elongate, laterally compressed, the greatest depth 2.3
(2.3 to 2.5) in the standard length. Head profile conical, the head length
contained 3.5 (3.0 to 3.2) in the standard length. The following proportions
are expressed into the head length: snout 4.4 (4.2 to 4.7), eye diameter 2.8
(2.5 to 3.0), interorbital width 3.2 (3.3 to 4.0), least depth of caudal peduncle
2.6 (2.2 to 2.7), length of caudal peduncle 2.2 (2.2 to 2.5), of pectoral
fin 0.9 (1.0 to 1.1), of pelvic fin 1.0 (1.1 to 1.2), of caudal fin 0.8 (0.9 to
1.1).
Single nasal opening on each side of snout; mouth oblique, terminally
located; lateral-line gently arched beneath dorsal fin, terminating Fh scale
rows below middle of soft dorsal fin; tip of snout, lips, chin, and isthmus
naked; remainder of head and body scaled; scales finely ctenoid; preopercle
'with two large scale rows and row of smaller scales on inferior and posterior
limb; small sheath scales covering basal 1/2 to 3/4 of membranous portions
of dorsal and anal fins and most of caudal; edge of suborbital hidden; rear
margin of preopercle entire or slightly crenulate; edge of bones of opercle
series entire except a single flattened spine on upper portion of opercle.
Teeth of jaws conical, multiserial, about 40 to 46 in outer row of upper
jaw and 34 to 42 in outer row of lower jaw; teeth at front of jaws slightly
enlarged, the largest about 1.0 to 1.5 nostril diameter; irregular series of
smaller teeth behind outer row teeth at front of jaws.
Origin of dorsal fin at level of third tubed scale of lateral-line; spines of
dorsal fin gradually increasing in length to about sixth or seventh spine,
remaining spines gradually decreasing in length. The following proportions
are expressed into the head length: 'length of first dorsal spine 4.0 (3.3 to
4.8), of seventh dorsal spine 2.1 (2.0 to 2.3), of last dorsal spine 2.7 (2.5 to
3.2), of last dorsal spine 2.7 (2.5 to 3.2), of longest soft dorsal ray 1.5
142

(1.5 to 1.7), of first anal spine 6.9 (4.3 to 5.9), of second anal spine 1.8
(1.6 to 1.9), of longest soft anal ray 1.7 (1.5 to 1.8).
Colour of holotype in alcohol: ground colour of head and body brown,
darker dorsally, grading to silvery on breast and abdomen; dorsal and anal
fins brown except posteriormost portion translucent; pectoral fins pale with
black spot in axil and invading upper half of outer pectoral base; pelvic fins
slightly dusky; caudal fin with broad dark streak on each lobe, inner portion
of fork pale. There is considerable variation in the ground colour of the
paratypes. Generally the specimens which have been in preservative for
several years are pale yellowish-brown to tan.
Colour in life: live colours are similar to those described above except
there is a small white spot, less than pupil size, below the base of the
posteriormost dorsal rays. In addition, the dorsal, anal, and caudal fins
have a narrow blue margin.
Remarks
McKay (1970) reported five specimens of an unidentified Chromis from
the Houtman Abrolhos and Shark Bay. They are identifiable as C. westaustralis
and are among the designated paratypes. McKay also indicated that
the record of C. scotochilopterus (non Fowler) by Whitley (1948) was
incorrect and refers to this species.
C. westaustralis is closely allied to C. fumea Tanaka which is known from
Taiwan, the Ryukyu Islands and Western Australia. The latter locality
represents a new locality record which is based on four specimens, 32.5-55.0
mm SL, at BPBM and WAM from Northwest Cape and Kendrew Island,
Dampier Archipelago.
Both species have the same general shape and are similar in coloration,
particularly with regards to the dark caudal streaks and small white spot in
live individuals at the base of the posterior dorsal rays. However, they differ
in several important respects. C. westaustralis generally has an additional soft
anal ray (11 vs 10 for C. fumea) and lacks the distinct preopercle serrae
which are typical of C. fumea. Furthermore, the black spot on the
pectoral axil of C. westaustralis extends onto the outer portion of the
pectoral base, covering most of the upper half. Finally, there appears to be a
significant difference ,in maximum size. The largest of many individuals of
C. fumea observed at Northwest Cape and the Dampier Archipelago was
approximately 60 mm SL compared with many species of-C. westaustralis in
excess of 80 mm SL seen at the Abrolhos Islands.
The species inhabits coral areas androcky reefs at depths ranging from two
metres to at least 75 metres. Over the southern portion of its range
143

c. westaustralis is usually encountered at depths greater than 25 metres, but
on the coral reefs of the Houtman Abrolhos (between 28 and 29°S latitude)
it is